Impurity Introducing Method, Impurity Introducing Apparatus, and Electronic Device Produced by Using Those

ABSTRACT

A subject of the present invention is to realize an impurity doping not to bring about a rise of a substrate temperature. 
     Another subject of the present invention is to measure optically physical properties of a lattice defect generated by the impurity doping step to control such that subsequent steps are optimized. 
     An impurity doping method, includes a step of doping an impurity into a surface of a solid state base body, a step of measuring an optical characteristic of an area into which the impurity is doped, a step of selecting annealing conditions based on a measurement result to meet the optical characteristic of the area into which the impurity is doped, and a step of annealing the area into which the impurity is doped, based on the selected annealing conditions.

TECHNICAL FIELD

The present invention relates to an impurity doping method, an impuritydoping system, and an electronic device formed by using them and, moreparticularly, an impurity doping applied in forming a semiconductordevice, especially the electronic device, or a liquid crystal panelmanufacturing method.

BACKGROUND ART

The technology to form a shallow junction is demanded in recent yearswith the miniaturization of the semiconductor device. In thesemiconductor manufacturing technology in the prior art, the method ofion-implanting various conductivity types of impurities such as boron(B), phosphorus (P), arsenic (As), and the like into a surface of asemiconductor substrate as a solid state base body at a low energy iswidely employed.

Since a semiconductor device having a shallow junction is formed byusing this ion-implanting method, a shallow junction can be formedactually, though there is a limit to a depth that can be formed by theion implantation. For example, because a boron impurity is hard to dopeshallowly, a limit of a depth of a doped area formed by the ionimplantation is at almost 100 nm from a surface of the base body.

Therefore, recently various doping methods have been proposed as theapproach of making a shallower junction possible. Out of them, muchattention is now focused on the plasma doping technology as thetechnology that is suited to practical use. This plasma doping is thetechnology that excites a reaction gas containing a doped impurity bythe plasma and irradiates the plasma onto a surface of the solid statebase body to dope the impurity. Then, activation of the doped impurityis carried out by the annealing step after the impurity is doped.

Normally, a light source that can emit an electromagnetic wave in a widewavelength range such as a visible radiation, an infrared radiation, aultraviolet radiation, and the like is employed in the annealing step.However, a wavelength effective for the activation is differencedepending on a crystal condition of the solid state base body itselfinto which the impurity is doped. Actually such wavelength often existsin a narrow range. An irradiation of the light of unnecessarywavelengths raises a temperature of the substrate and causes thecharacteristic deterioration in some cases.

In recent years, the method of measuring a quantity of impurity doped ina surface of a solid state base body by the optical measurement has beenproposed (see JP-A-2000-282425, for example). Since this method measuresa quantity of radical by the optical measurement, a doping amount can bemeasured by sensing an amount of current.

DISCLOSURE OF THE INVENTION

A doped amount of the impurity, i.e., a total amount of impurity dopedinto the solid state base body is sensed by the above method. Certainlyit is important to measure a total amount of doped impurity. But it isextremely important to sense a condition such as a crystal condition inthe impurity doped area, i.e. how many lattice defects are introducedwhen the semiconductor device is formed by doping the impurity into asilicon substrate or when a liquid crystal panel is manufactured byforming TFTs (thin film transistors) on a liquid crystal substrate, inrealizing the optimal plasma doping and the optimal annealingsubsequently executed by an energy irradiation such as a lightirradiation, or the like.

The present invention has been made in view of the above circumstances,and aims at providing the impurity doping technology that realizes anelectrical activation of an impurity not to bring about a temperaturerise of a substrate.

Also, the present invention aims at measuring optically physicalproperties of a lattice defect generated in a single crystal silicon ora polycrystalline silicon by the impurity doping step while asemiconductor device is formed on a silicon substrate, a liquid crystalpanel is manufactured, or the like, and then controlling conditions ofthe impurity doping step to optimize the conditions in subsequent steps.

Therefore, an impurity doping method of the present invention, includesa step of doping an impurity into a surface of a solid state base body;a step of measuring an optical characteristic of an area into which theimpurity is doped; a step of selecting annealing conditions based on ameasurement result to meet the optical characteristic of the area intowhich the impurity is doped; and a step of annealing the area into whichthe impurity is doped, based on the selected annealing conditions.

According to this method, the optical characteristic of the area intowhich the impurity is doped are measured previously, and the optimumannealing can be realized in response to the optical characteristic,whereby the impurity doped area can be formed highly effectively withhigh precision.

In this case, the impurity doping step contains not only the step ofdoping the impurity simply but also the step of controlling a surfacecondition to get the optical characteristic suitable for the annealingstep such that the energy can be absorbed effectively in the annealingstep containing mainly the light irradiation subsequently executed. Thecontrol of the optical characteristic contains a step of controlling acomposition of the plasma by changing a mixture ratio between animpurity substance to constitute the plasma and an inert substance or areactive substance as a substance mixed with the impurity substance, tocontrol the optical characteristic of the area into which the impurityis doped. That is, the step of supplying the impurity substance onto thesurface of the solid state base body simultaneously or sequentially withthe inert substance such as a nitrogen, a rare gas, or the like and thereactive substance such as an oxygen, a silane, a disilane, or the likeand then forming the optical characteristics suitable for the annealingstep is contained. The “impurity doping method” in the present inventionindicates a series of steps containing the annealing step.

Also, in the present invention, the step of doping the impurity containsa plasma doping step.

According to this method, the impurity can be doped in a shallow area.

Also, in the present invention, the step of doping the impurity containsan ion implanting step.

According to this method, the annealing step consisting mainly of thelight irradiation executed subsequently can be made highly effective,and also the high-precision plasma doping can be accomplished.

Also, in the present invention, the measuring step is executed prior tothe annealing step.

According to this method, the condition of the area into which theimpurity is doped can be sensed before the annealing, and the annealingconditions can be selected thereafter, whereby the optimum activationstate can be obtained.

Also, in the present invention, the measuring step is executed inparallel with the annealing step.

According to this method, the condition of the area into which theimpurity is doped can be sensed during the annealing, and the annealingconditions can be selected thereafter, whereby the optimum activationstate can be obtained.

Also, in the present invention, the annealing step is divided intoplural numbers of time, and the measuring step is executed among theannealing step.

According to this method, the annealing step is divided into pluralnumbers of time, the condition of the area into which the impurity isdoped can be sensed during the annealing, and the annealing conditionscan be selected thereafter. Thus, the optimum activation state can beobtained.

Also, in the present invention, the step of selecting the annealingconditions contains a step of causing the annealing conditions to changesequentially following upon a change of the optical characteristic ofthe impurity doped area during the annealing step.

According to this method, the change of the area into which the impurityis doped by the annealing can be sensed, and the annealing conditionscan be selected thereafter. Thus, the optimum activation state can beobtained.

Also, in the present invention, the impurity doping step is divided intoplural numbers of time, and the measuring step is executed among theimpurity doping step.

According to this method, since the measuring step is executed among theimpurity doping step, the optical characteristic can be measureprecisely according to the situation in the chamber in the impuritydoping step and also the high-precision impurity doping can be realized.Also, though the doping of the impurity must be stopped once, thisexample is effective for the doping using the atmospheric pressureplasma, or the like.

An impurity doping method of the present invention, includes a step ofdoping an impurity into a surface of a solid state base body; a step ofmeasuring an optical characteristic of an area into which the impurityis doped; a step of adjusting the optical characteristic based on ameasurement result to meet annealing conditions; and a step of annealingan area into which the impurity is doped.

This method is effective for the case where there is a restriction onthe annealing conditions.

Also, in the present invention, plasma doping conditions are controlledsuch that optical constants meet a light irradiation executed after theplasma doping step, while monitoring the optical constants of the areainto which the impurity is doped.

According to this method, the impurity doped area having ahigher-precision depth and dosage can be formed. Here, as the opticalconstant, the reflectance, or the like can be applied in addition to thelight absorption coefficient.

Also, in the present invention, the measuring step is a step of using anellipsometry.

Also, in the present invention, the step of using the ellipsometrycontains an ellipsometry analyzing step of calculating both a thicknessof the impurity doped layer and optical constants (a refractive index nand an extinction coefficient k).

Also, in the present invention, the ellipsometry analyzing step containsan analyzing step employing a refractive index wavelength dispersivemodel using any one of K-K (Kramers-Kronig) analysis, Tauc-Lorentzanalysis, Cody-Lorentz analysis, Forouhi-Bloomer analysis, MDF analysis,band analysis, Tetrahedral analysis, Drude analysis, and Lorentzanalysis. It is particularly desirable to employ the refractive indexwavelength dispersive model since the absorption characteristic can behandled.

Also, in the present invention, the measuring step contains a step ofusing XPS in the impurity doping method.

Also, in the present invention, the annealing step is a step ofirradiating an electromagnetic wave.

Also, in the present invention, the annealing step is a step ofirradiating a light.

Also, in the present invention, the step of doping the impurity is astep of doping an impurity such that a light absorption coefficient ofthe area into which the impurity is doped exceeds 5 E⁴ cm⁻¹.

According to this method, the annealing conditions having the high lightabsorbency and the high efficiency can be selected.

Also, in the present invention, the plasma doping step contains a stepof controlling at least one of a power supply voltage applied to theplasma, a composition of the plasma, and a ratio between an irradiationtime of the plasma containing a dopant substance and an irradiation timeof the plasma not containing the dopant substance.

According to this method, the effective control can be executed. Here,the composition of the plasma is controlled by adjusting a mixture ratiobetween the impurity substance as the dopant and other substance, avacuum, a mixture ratio between other substances, etc.

Also, in the present invention, the plasma doping step contains a stepof controlling a composition of the plasma by changing a mixture ratiobetween an impurity substance to constitute the plasma and an inertsubstance or a reactive substance as a substance mixed with the impuritysubstance, to control the optical characteristic of the area into whichthe impurity is doped. Here, the optical characteristics are controlledby changing a mixture ratio among the substance such as arsenic,phosphorous, boron, aluminum, antimony, indium, or the like as theimpurity substance, the inert gas such as helium, argon, xenon, or thelike as the mixed substance, and the reactive substance such asnitrogen, oxygen, silane, disilane, or the like.

Also, in the present invention, the plasma doping step sets the opticalconstant of the area into which the impurity is doped such thatelectrical activation of the impurity contained in the area into whichthe impurity is doped is accelerated and an energy absorption into thesolid state base body is suppressed.

According to this method, the annealing can be accomplished selectivelyeffectively not to increase a temperature.

An impurity doping system of the present invention, includes an impuritydoping means for doping an impurity into a surface of a solid state basebody; a measuring means for measuring an optical characteristic of anarea into which the impurity is doped; and an annealing means forannealing the area into which the impurity is doped.

Accordingly, the surface condition can be sensed easily.

Also, in the present invention, the impurity doping system furtherincludes a doping controlling means for controlling the plasma dopingmeans based on measurement results of the measuring means.

Also, in the present invention, the impurity doping system furtherincludes an annealing controlling means for controlling the annealingmeans based on measurement results of the measuring means.

Also, in the present invention, the impurity doping system furtherincludes a feedback mechanism for feeding back a measurement result ofthe measuring means to any one of the annealing controlling means or theimpurity doping controlling means.

Also, in the present invention, the feedback mechanism executes afeedback of a measurement result in-situ.

Also, in the present invention, the feedback mechanism executes asampling inspection at a high speed, and executes an additional processsuch as an additional doping, annealing conditions relaxation, or thelike if a result is not good.

Also, an electronic device of the present invention formed by doping animpurity by using the impurity doping method of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view explaining an optical measurement of an impurity dopedlayer generated in vicinity of a surface of a solid state base body in afirst embodiment of the present invention,

FIG. 2 is a configurative view of a spectroellipsometer used to explaina method of deriving a thickness of the impurity doped layer and a lightabsorption coefficient,

FIG. 3 is a graph showing the light absorption coefficient of theimpurity doped layer measured by the ellipsometer,

FIG. 4 is a sectional configurative view showing a system used in theinvention of this application that employs a plasma doping method in asecond embodiment of the present invention,

FIG. 5 is a graph showing spectra of absorption coefficients of samplesPD-1 (bias voltage 30 V, process time 60 s) and PD-2 (bias voltage 60 V,process time 60 s), and a crystalline silicon substrate for the sake ofcomparison,

FIG. 6 is graphs showing a dependency of the light absorptioncoefficient on a process time (a) and a wavelength (b) in the impuritydoping method in Example 3 of the present invention,

FIG. 7 is an explanatory view of an annealing furnace using a whitelight source in Example 6 of the present invention and a wavelengthselecting filter,

FIG. 8 is schematic sectional views of a solid state base body used toexplain a special effect when the impurity doped layer in Example 7 ofthe present invention is nitrided or oxidized,

FIG. 9 a system conceptual view of the annealing furnace in Example 7 ofthe present invention, and

FIG. 10 is a graph explaining an example in which a light of awavelength that responds to a transition of time is irradiated inannealing the impurity doped layer.

In Figures, a reference numeral 100 is a solid state base body, 110 animpurity doped layer, 120 a light source, 130 a photometer, 200 a vacuumchamber, 210 a vacuum pump, 230 a vacuum gauge, 240 a plasma source, 250a power supply, 260 a substrate holder, 270 a power supply, 280 a firstline, 290 a second line, 300 a third line, 310 a plasma, 320 a computer,340 a control circuit, 350 a controller, 500 a substrate holder, 510 awhile light source, 520 a filter, 530 a selected light, 600 a nitridedlight, 610 an oxidized light, 700 a laser light source, 710 a modulationfilter, and 720 a modulated light.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be explainedhereinafter.

The present invention gives roughly three embodiments. The first of theembodiments resides in that conditions of the impurity doped into thesolid state base body is sensed by the optical measurement. Thissignifies not only the optical measurement of the impurity itself butalso the optical measurement of the “composite layer” conditionincluding the crystal condition of the solid state base body itself, thephysical change of the crystal condition of the solid state base bodysuch as a damage caused by an energy applied in the doping, or the like,and the chemical change of the solid state base body such as ageneration of a oxide layer/a nitride layer, or the like. The second ofthe embodiments resides in that the annealing conditions are optimizedaccording to the sensed conditions of the impurity. The third of theembodiments resides in that the doping of the impurity is controlled tomeet the annealing conditions.

In other words, in the method of the present invention, a quality of theimpurity doping is improved further by applying a feedback control tothe doping of the impurity after conditions of the impurity are grasped.Also, for example, in the semiconductor device or the liquid crystaldisplay as the major application field of the present invention, theimpurity in the semiconductor is activated electrically by supplying theenergy to the base body by virtue of any method after the impurity isintroduced into the solid state base body. In order to derive the bestresult in this step, the steps applied while the impurity is being dopedare controlled.

Embodiment 1

In the present embodiment 1, a method of doping the impurity into thesolid state base body by using particles having an energy (several tenseV or more) that is sufficiently higher than a bond energy of thelattice will be explained hereunder. When the particles having theenergy (several tens eV or more) that is higher sufficiently than thebond energy of the lattice in doping the impurity into this solid statebase body, formation of the lattice defect in the lattices, whichconstitute the crystalline or noncrystalline substance to construct thesolid state base body, and the impurity substance itself cause physicalproperties of the solid state base body to change, so that an impuritydoped layer (new second layer) 110 having physical properties that aredifferent from a solid state base body 100 is formed.

Also, in the step of doping the impurity with a relatively small dopingenergy applied when a thermal equilibrium condition is changed, or thelike, the impurity doping step causes the physical properties of thesolid state base body to change and subsequently the new (second) layer110 made mainly of the impurity substance itself is formed in closevicinity of a surface of the solid state base body.

Therefore, according to the ellipsometry, as shown in FIG. 1, a light isirradiated onto the surface of the solid state base body by using alight source 120 and then the light is measured by a photometer 130.

A method of measuring a thickness of an impurity doped layer and a lightabsorption coefficient by using the ellipsometry will be explained withreference to a configurative view of a spectroellipsometer in FIG. 2hereunder.

As shown in FIG. 2, this spectroellipsometer includes a Xe light source20, a polarizer 21 for polarizing a Xe light output from this lightsource to irradiate onto a substrate as a sample 11, an analyzer 22 forsensing a reflected light from the sample 11, a spectrometer 23, and adetector 24. Here, the Xe light output from the Xe light source 20 isconverted into a linearly polarized light by the polarizer 21, and thenis incident onto the substrate at an angle 00 to the directionperpendicular to the substrate surface. This angle θ₀ is fixed to θ₀=70°in this measurement, but the measurement can be done if this angle ischanged in a range of 45° to 90°. An axis of the linear polarization ofthe incident light is tilted with respect to a p-direction (direction ofa line of intersection between a plane perpendicular to an optical axisand a plane containing the incident light and the reflected light) andan s-direction (direction perpendicular to the p-direction in the planeperpendicular to the optical axis). Assume that an amplitude reflectanceratio between a p-component and an s-component of the light reflected asan elliptically polarized light is Ψ and a phase difference between thep-component and the s-component is Δ. The ellipsometry is constructedsuch that the light reflected as the elliptically polarized light isincident on the spectrometer 23 via the analyzer 22, and then Ψ and Δare measured by the detector 24 while analyzing the light by thespectroscope.

A method of deriving not only a thickness of the impurity doped layerbut also optical constants (a refractive index n and an extinctioncoefficient k) as an unknown parameter based on the ellipsometrymeasurement results of Ψ, Δ by the method of least squares will beexplained hereunder. The impurity doped layer is referred to as a PDlayer, and three-layered model consisting of Air/PD layer/c-Si was used.Since the optical coefficient has the wavelength dependency, unknownparameters are increased as many as the number of measured wavelengthswhen the measurement is done while changing a wavelength, so that theunknown parameters cannot be derived. In such case, spectra of theoptical coefficients can be derived if such spectra of the opticalcoefficients are expressed by the approximate expression containingconstants that do not depend on the wavelength and then the constantsare used as the unknown parameters.

As the refractive index wavelength dispersive model, various exampleshave been proposed. Because the strong absorption characteristic of thePD layer must be handled, the K-K (Kramers-Kronig) analysis method wasused in the present embodiment. Even when Tauc-Lorentz analysis,Cody-Lorentz analysis, Forouhi-Bloomer analysis, MDF analysis, bandanalysis, Tetrahedral analysis, Drude analysis, Lorentz analysis, or thelike is employed as the refractive index wavelength dispersive model,the above analysis can be conducted.

Next, the feature of the K-K (Kramers-Kronig) analysis method will beexplained hereunder.

When a light absorption band of a thin film layer is present within ameasured wavelength range, not only the refractive index but also theextinction coefficient can be derived by using the dispersion formula(Equation 1) of the complex refractive index derived from a followingKramers-Kronig relations.

$\quad\begin{matrix}{{Formula}\mspace{14mu} 1} & \; \\\begin{matrix}{n = {1 + {\frac{2}{\pi}P{\int_{0}^{\infty}{\frac{\omega^{\prime}k}{\omega^{\prime 2} - \omega^{\prime 2}}\ {\omega^{\prime}}}}}}} \\{k = {{- \frac{2}{\pi}}P{\int_{0}^{\infty}{\frac{\omega^{\prime}k}{\omega^{\prime 2} - \omega^{\prime 2}}\ {\omega^{\prime}}}}}}\end{matrix} & (1)\end{matrix}$

where P is a principal value of Cauchy integral, and ω is a frequency.

These relations indicate that, if the extinction coefficient has alreadybeen known, the refractive index can be estimated based on theextinction coefficient. When a light absorption band is present within ameasured wavelength range, the spectrum of the extinction coefficient inthe wavelength range is approximated by the Lorentz-type formula(Equation 2).

Formula 2

k=C1(E−C4)²/(E ² −C2E+C3)   (2)

where E is a photon energy (eV), and has a relation with a wavelength λ(nm) shown in following Equation (3).

Formula 3

E(eV)=1239.84/λ(nm)   (3)

A following Equation (4) of the refractive index can be derived byintegrating the Kramers-Kronig relations (1) while using Equation 2.

Formula 4

n=C5+f(E)   (4)

where f(E) is an integrated value, and C5 is an integration constant.

In this K-K analysis, C1, C2, C3, C4, C5 act as parameters and givesinitial values. Since C5 is one of parameters representing therefractive index by the integration constant, the rough refractive indexof the PD layer is set as an initial value. In C1, the rough extinctioncoefficient, i.e., the value of the peak extinction coefficient of theextinction coefficient spectrum gives an initial value.

In contrast, C2, C3 are relevant to the peak E (eV) of the extinctioncoefficient spectrum, and C2 can have a twice value of the peak E (eV)as the rough initial value whereas C3 can have a square value of thepeak E (eV) as the rough initial value. Since C4 is related to an energyband width of the absorption band, the E (eV) value that has thesmallest extinction coefficient at a foot of the peak of the extinctioncoefficient spectrum can be used as an initial value.

As described above, when the K-K analysis is employed, the analysis canbe made if the initial value is set by assuming the absorption spectrum,i.e., the extinction coefficient spectrum, while taking the physicalproperties of the thin film as the object substance in the measurementinto account.

In the K-K analysis model, the setting of parameters is difficult incontrast to other models and also the fitting calculation is difficult.No fitting can be obtained according to the setting of the parameters.Therefore, the K-K analysis must be employed after the user becomesfamiliar with the measurement analysis to some extent and understandsthe characteristics of the model.

After the thickness of the impurity doped layer and the opticalconstants (the refractive index n and the extinction coefficient k) aredetected by the above method, the light absorption coefficient can becalculated by a following Equation (5).

α=4πk/λ  (5)

A spectrum representing the optical characteristics of the impuritydoped layer 110 is shown in FIG. 3.

As apparent from FIG. 3, when considered based on the measurement resultusing the ellipsometry, the light absorption coefficient the lightbetween a wavelength 300 nm to 600 nm is increased.

Therefore, the activation can be effectively attained by irradiating thelight having the wavelength 300 nm to 600 nm in the subsequent step, andthus the impurity can be activated effectively by a smaller irradiationenergy.

In this manner, in the present embodiment, the surface condition of thesolid state base body into which the impurity is introduced aremeasured, and then the main factors in the subsequent step are decidedbased on the measurement result.

Meanwhile, in the semiconductor industry or the liquid crystal industry,the impurity doped layer 110 formed by doping the impurity is activatedelectrically by irradiating an electromagnetic wave. This means that thecrystals of silicon as the major constituent element of the solid statebase body are destroyed by the step of doping the impurity at an energyhigher than a bond energy of the lattice, then the lattice defects thatare introduced into the impurity doped layer (the impurity doped area)are recovered by irradiating the electromagnetic wave onto the impuritydoped layer in the subsequent step, and then the impurity doped layer ischanged into the electrically active condition.

At this time, the condition of the impurity doped layer depends on arelationship between physical properties of the substance constitutingthe solid state base body and the impurity substance. The impuritysubstance enters into the lattice position of the silicon, for example,by the substitution, and the crystallization is accelerated and thus theimpurity doped layer becomes the electrically active condition.

Therefore, in order to realize such process, the impurity iselectrically activated effectively in irradiating a visible radiation,for example. Here, it is desirable that the light absorbing spectrum ofthe impurity doped layer should be analyzed and then the light of anadequate wavelength should be irradiated based on the result. Also, whenthe solid state base body 100 and the impurity doped layer 110 are mixedtogether on the surface, the light absorbing spectrum of the solid statebase body itself is analyzed, then the wavelength band in which thelight absorption coefficient of the solid state base body 100 is smallbut the light absorption coefficient of the impurity doped layer 110 islarge is selected, and then the light in this wavelength band isirradiated. Thus, the impurity doped layer can be activated whilesuppressing a temperature rise of the solid state base body 100.

As described above, in the present embodiment, because the opticalmeasurement utilizing the ellipsometry is used, the light absorptioncoefficient can be calculated correspondingly. In particular, since adiffusion phenomenon generated in the solid state base body acts as amajor factor to prevent the miniaturization in forming the fine devicehaving a small size, the irradiation of a light of a particularwavelength only can prevent the diffusion in a sense of providing nouseless energy to the solid state base body, and thus the presentembodiment is effective for the formation of the fine device. Especiallya large number of thermal treatment processes must be applied when alarge number of impurity doping steps are contained. According to thepresent invention, extension of an unnecessary diffusion length can besuppressed by irradiating only the light of the particular wavelength.

In this case, the optical characteristic measuring method is not limitedto the ellipsometry, and XPS, or the like can be selected appropriately.

Embodiment 2

Next, a method of employing a plasma doping method as the impuritydoping method while using this method will be explained hereunder.

First, a plasma doping system and an impurity doping controlling systemused in the present embodiment will be explained, and then several typesof controlling method will be described in detail. As shown in FIG. 4,the plasma doping system employed in the present embodiment includes thelight source 120 and the photometer 130 as the measuring means formeasuring the optical characteristics of the impurity doped area on thesolid state base body 100, and a controlling means for controlling thedoping conditions based on the optical characteristics obtained by thismeasuring means. This system feedback-controls the doping conditionssuch that the optimum surface condition can be obtained.

In other words, this plasma doping system includes a vacuum chamber 200,and a plasma source 240 for generating the plasma in the vacuum chamber200, and applies the plasma doping onto the surface of the solid statebase body 100 loaded on a substrate holder 260 as the processed basebody.

Then, a vacuum pump 210 is connected to this vacuum chamber 200, and avacuum gauge 230 for measuring a vacuum is provided to the vacuumchamber 200. A power supply 250 is connected to the plasma source 240.Also, a power supply 270 for applying a unique electrical potential isconnected to the substrate holder 260 separately from the above powersupply.

Also, a gas introducing mechanism for introducing these gases isprovided to the vacuum chamber 200. This gas introducing mechanism isconstructed by a first line 280 for supplying a first substance as adopant substance, a second line 290 for supplying a second substance (Hein this case) as other substance, and a third line 300 for supplying athird substance (Ar in this case).

Also, the controlling means includes a computer 320 for computing theoptical characteristics measured by the photometer, a control circuit340 for deciding the controlling conditions based on the computedresult, and a controller 350 for feedback-controlling the dopingconditions of the plasma doping system based on an output of the controlcircuit.

Next, a doping method using this doping system will be explainedhereunder.

Here, the case where a gas is utilized as a doping source will beexplained hereunder.

First, the dopant substance as the first substance is supplied to thevacuum chamber 200. Here, other substance different from this dopantsubstance is introduced as a carrier gas or the material that possessesa particular function. In the present embodiment, a gas having differentproperties from the dopant substance, e.g., a rare gas, or the like,which does not become electrically active in the silicon, is selected.By way of example, there is He or Ar. Then, He is selected as the secondsubstance, and Ar is selected as the third substance. Then, a plasma 310is generated on the surface of the solid state base body 100 in thevacuum chamber 200 by introducing the gases from the. gas introducinglines consisting of the first to third lines 280, 290, 300.

The charged particles in the plasma are attracted by an electricpotential difference between the plasma 310 and the solid state basebody 100, so that the impurity doping is applied. At the same time, theelectrical neutral substances in the plasma are adhered or occluded invicinity of the surface of the solid state base body 100. Here, thecondition of the impurity doped layer 110 is decided by the condition ofthe underlying solid state base body 100 and the energy of the plasma,and the impurity may be adhered or may be occluded.

According to this impurity doping step, the impurity doped layer 110explained in the above embodiment is formed on the surface of the solidstate base body 100. In order to measure the physical properties of theimpurity doped layer, the light source 120 and the photometer 130 areprovided to the vacuum chamber 200. Then, the optical characteristicsmeasured by the photometer 130 are computed by the computer 320, thenthe computed result is fed to the control circuit 340, and then the dataare fed to the controller 350 as feedback information, whereby theplasma doping system adjusts the plasma conditions and controls thephysical properties of the impurity doped layer.

As the plasma conditions to be adjusted here, there are a power supplyvoltage applied to the plasma or a voltage application time and anapplication timing, a mixture ratio of the dopant substance and othersubstance, a vacuum degree, a mixture ratio of other substances, a ratiobetween an irradiation time of the plasma containing the dopantsubstance and an irradiation time of the plasma not containing thedopant substance, and others. The physical properties of the impuritydoped layer are controlled by changing these parameters.

As Examples of the present invention, respective examples in which theseparameters are changed will be explained subsequently hereunder. Now themethod of mixing a power and a gas will be described in detail herein.

EXAMPLES Example 1

First, a method of changing a power will be explained as Example 1.

It has already been known that a plasma density and an energy of thecharged particles (mainly positively charged ions) reaching thesubstrate are decided depending on a power supplied to generate theplasma and a power supply connected to the substrate holder. An examplein which a power of the power supply 270 connected to the substrateholder 260 is changed mainly will be described herein.

First, a power of 1000 W was supplied from the power supply 250 used togenerate the plasma. In order to cause this generated plasma 310 toreach effectively the substrate, a power was supplied to the substrateholder 260. First, the plasma doping was started by supplying 100 W. Atthis time, a thickness of the impurity doped layer needed finally wasset to 15 nm.

Here, a dopant substance B₂H₆ was employed and also He was employed asother substance. B₂H₆ is introduced by 2 SCCM and He is introduced by 10SCCM. A vacuum was set to 1 Pa. First, the doping was executed for 5second while 100 W was being supplied from the power supply 250.

In this state, as shown in FIG. 1 and FIG. 4, the optical constant(light absorption coefficient) of the impurity doped layer was measuredby the photometer 130. As a result, it was found that a thickness of theimpurity doped layer, as the result computed by the computer 320, is 12nm.

Then, the conditions applied to set a thickness of the impurity dopedlayer to 15 nm were calculated by the control circuit 340, based on adatabase formed based on the measurement result measured by theinventors themselves. Then, the controller 350 increased a powersupplied from the power supply 250 up to 115 W based on the calculatedresult, and then the plasma doping was carried out for 3 second.

Then, it was confirmed by the photometer 130 that a thickness of theimpurity doped layer comes up to 15 nm. Then, the power supply 250 wasturned OFF, then the plasma 310 was put out, and then the process wasended.

Example 2

Spectra of absorption coefficients of samples PD-1 (bias voltage 30 V,process time 60 s) and PD-2 (bias voltage 60 V, process time 60 s), anda crystalline silicon substrate for the sake of comparison, which werederived by using the K-K (Kramers-Kronig) analysis method, are shown inFIG. 5. In this case, when the bias power supply voltage was increasedwithin a wavelength range of 400 nm to 800 nm for a same plasma dopingtime of 60 sec, the light absorption coefficient of the PD layer wasincreased. This result concluded that PD-2 is suitable for the casewhere the annealing method using the wavelength of 400 nm to 800 nm, forexample, is employed. That is, the ellipsometry measurement result couldbe fed back to the optimization of the annealing, so that the validityof the ellipsometry measurement using the K-K (Kramers-Kronig) analysismethod was verified.

Example 3

Next, an example in which a method of mixing a gas in the impuritydoping step is controlled will be explained hereunder as Example 3.

When the silicon substrate was utilized as the solid state base body100, for example, in forming the impurity doped layer 110, the crystallattices were disturbed by the dopant substance and other substances andthus such substrate become its amorphous state. It filled the importantrole in the subsequent step to convert this amorphous state to a desiredstate.

In this Example, BF₃ was used as the dopant substance and He and Ar wereused as other substances. Here, a quantity of BF₃ serving as the dopantsubstance was kept constant, but a thickness of the impurity doped layer110 was changed.

First, the plasma was generated for 5 sec by introducing Ar to form apart of the impurity doped layer 110. A thickness of the impurity dopedlayer 110, when measured by the photometer, was 5 nm. Then, BF₃ wasintroduced into the doped impurity doped layer 110, and gas-adsorptionwas applied for 5 sec. Then, the BF₃ plasma was generated by supplying apower, and then the doping was continued for 3 sec. At the same time, Hewas introduced to get a thickness of 20 nm at 100 W as a relativelysmall power. A supply of BF₃ was stopped after a quantity of the dopantcome up to a predetermined dopant quantity. The He plasma irradiationwas continued while measuring a thickness by the photometer. When it wasconfirmed that an optical thickness of the impurity doped layer reaches20 nm after 5 sec elapsed, the plasma was stopped and the process wasended.

Example 4

Next, an example in which a ratio between an irradiation time of theplasma containing the dopant substance and an irradiation time of theplasma not containing the dopant substance is adjusted will be explainedhereunder as Example 4. In order to simplify the explanation, theoptical properties of the solid state base body, especially an examplein which the impurity doped layer 110 having the large light absorptioncoefficient in the annealing such as the light irradiation, or the likeexecuted subsequently after the doping process is formed, will beexplained herein. For example, when the plasma doping system shown inFIG. 4 is employed, normally such a case was supposed that the lightabsorption coefficient of the impurity doped layer 110, which is formedby the plasma doping using a necessary quantity of dopant, is inadequatefor the annealing.

At that time, only the light absorption coefficient is adjusted to havea large value and not to vary a dopant quantity, then a rare gas, e.g.,Ar is introduced from the second line 290 to dope the second substancesuch that a predetermined light absorption coefficient in the annealingcan be set, and then another plasma different from the dopant is formedand irradiated onto the solid state base body. Although a mere singleexample, the impurity doped layer 110 is formed by irradiating the Arplasma onto the solid state base body 100 for 5 sec. At that time, aplasma irradiation time and other plasma parameters are adjusted suchthat the light absorption coefficient has a large value enough toexecute subsequently the annealing. Then, a gas obtained by dilutingB₂H₆ with He to 0.5% is introduced from the first line 280 provided forthe dopant substance to generate the plasma, and then the plasma isirradiated for 15 sec.

The optical physical properties of the impurity doped layer 110 formedcompositely by using first the Ar plasma and then the dopant plasma weremeasured via the photometer 130, then predetermined opticalcharacteristics, i.e., the light absorption coefficient here, werederived via a series of control systems, and then the process was ended.FIG. 6( a) shows qualitatively a dependency of an increase of the lightabsorption coefficient on a process time at a time of Ar irradiation.The process was shifted to the dopant process after it was checked thatthe light absorption coefficient is increased in excess of 5 E⁴ cm⁻¹ forabout 5 sec.

According to this method, the effective annealing could also beachieved.

Example 5

Next, Example 5 of the present invention will be explained hereunder. Inthis Example, the optical characteristics of the impurity doped layer110 were also controlled by the feedback control, as in Examples 1 to 4.The case where a liquid crystal substrate is used as the solid statebase body 100 will be explained hereunder. In this case, apolycrystalline silicon was deposited on a glass or a quartz glasssubstrate, and then the impurity used to form TFTs was doped into thispolycrystalline silicon. Since such polycrystalline silicon deposited onthe glass substrate is a thin film, it is possible that a thickness ofthe impurity doped layer 110 formed in doping the impurity occupies mostof the thin film.

The light absorption coefficient was extracted from the opticalconstants measured by the photometer 130. In the formation of the liquidcrystal device, the method of irradiating the laser onto the impuritydoped layer to activate electrically it after the dopant substance isdoped was employed. Therefore, the impurity doped layer was adjusted andthe light absorption coefficient was controlled such that this laserlight can be absorbed effectively.

In this Example, the impurity doping system shown in FIG. 4 wasemployed, the optical characteristics of the impurity doped layer weremeasured by the photometer 130, and a doping quantity was adjusted whilefeeding back the measurement result. A supply of the dopant substancewas stopped according to the measurement result by the photometer 130,and the impurity doping process was ended.

According to this method, the activation could be attained effectively.Thus, a temperature rise of the glass substrate was small, generation ofwarp, distortion, crack, etc. could be suppressed, and a yield could beimproved.

Similarly this method can be controlled satisfactorily when othersubstance, e.g., the silicon substrate, is used as the solid state basebody.

Example 6

Next, Example 6 of the present invention will be explained hereunder.

In this Example, as shown in the embodiment 1, the opticalcharacteristics of the impurity doped layer 110 into which the impuritywas doped were measured, and then the activation of the impurity dopedlayer was attained by adjusting the annealing conditions in response tothe result not to raise a substrate temperature.

Here, the electromagnetic wave containing a particular wavelength wasirradiated onto the solid state base body 100, on which the impuritydoped layer 110 formed by the already-described method is formed, toanneal. An energy of the electromagnetic wave was employed to contributeparticularly effectively to the electrical activation of the impuritydoped layer, but a supply of energy to other areas (solid state basebody) was suppressed and a temperature rise of the solid state base body100 was suppressed.

Like the embodiment 1, a light was irradiated onto the impurity dopedlayer 110 formed on the surface of the solid state base body 100 fromthe light source 120, and then the light was measured by the photometer130. The spectrum representing the optical characteristics of theimpurity doped layer 110 is shown in FIG. 6( b). The spectrum in FIG. 6(b) was measured by utilizing the ellipsometry, and major factors of theannealing step as the next step were decided based on the measurementresult.

The boron was doped in the single crystal silicon substrate by theplasma doping in accordance with the method shown in the embodiment 2.

As the result obtained when the optical measurement of the solid statebase body 100 containing the impurity doped layer 110 formed at thistime was similarly taken, the spectrum having a peak near 600 nm wasobserved, as shown in FIG. 6( b). In this case, it is effective toirradiate only the light with a wavelength, which is effective for theannealing, onto the substrate having the impurity doped layer, whileemploying either the laser light that emits a light near 600 nm or thefilter to cut a wavelength except the wavelength of 580 nm to 620 nmwhen a white light source having a slightly wide peak, for example, isemployed.

For this reason, in this Example 6, an example in which the wavelengthcontrol is carried out by using a filter will be explained hereunder.

As shown in FIG. 7, this annealing furnace is constructed to have asubstrate holder 500, a while light source 510, and a filter 520provided detachably to transmit only a selected light 530 having aparticular wavelength from the while light source.

In this example, the solid state base body 100 on which the impuritydoped layer 110 was loaded on the substrate holder 500, and then thelight emitted from the while light source or adjusted via the filter tohave the predetermined wavelength was irradiated onto the impurity dopedlayer 110 formed on the surface of the solid state base body, and thusthe appropriate annealing was executed.

More particularly, the light source containing a particular wavelengthto form a peak in the wavelength spectrum shown in FIG. 6 was provided,and the filter 520 having such a characteristic that only a wavelengthsuited to anneal the substrate is passed (e.g., the characteristiccontaining a peak of the wavelength spectrum) was provided. In thissystem, the light 530 that is irradiated from the light source at anintensity of 100 W, i.e., the while light source 510 in this case andthen filtered within 580 nm to 620 nm by the filter 520 is irradiated.An energy of the light 530 being filtered in this manner was absorbedeffectively by the impurity doped layer 110 on the substrate andattenuated, and thus a quantity of energy absorbed by the solid statebase body 100 was very small.

In this way, a temperature of the overall solid state base body isseldom increased and the energy is absorbed only by the impurity dopedlayer 110, so that the impurity annealing layer limited within aparticular area can be formed. This method is very useful for forming aMOS transistor placed in a miniaturized range area, and the like.

Here, a cooling mechanism (not shown) may be provided to the substrateholder 500, and the substrate can be cooled further. However, accordingto the present invention, the effective energy can be absorbed by theimpurity doped layer 110, and therefore such cooling mechanism is not soneeded.

Further, when the light source 120 and the photometer 130 are providedto the annealing furnace shown in FIG. 7 by using the same mechanism asthat employed in the doping system shown in FIG. 4 and then the opticalproperties of the impurity doped layer 110 are measured, the change ofphysical properties in the light irradiation was measured. In thisfashion, the state change caused by the light irradiation could bemeasured.

In the above Examples, the light of a desired wavelength was irradiatedby using the white light source and the filter. In this Example, a laserlight source having an adequate wavelength (for example, 600 nm in thiscase) may be utilized in place of the white light source 510.

Conversely, the impurity doped layer having desired opticalcharacteristics may also be designed to conform to a wavelength of thelaser light source that is industrially available inexpensively.

Example 7

Next, a method of mixing a nitrogen and an oxygen as a mixed substanceupon the plasma doping will be explained hereunder, as Example 7 of thepresent invention. First, the impurity doped layer 110 of 10 nmthickness was formed on the solid state base body by the impurity dopingapplied by the method, described in the embodiment 2, while using thedoping system shown in FIG. 4.

Then, a nitrogen or a gas containing a nitrogen was introduced via thesecond line 290 that is used to introduce the second substance as othersubstance, then the plasma was generated, and then an upper portion ofthe impurity doped layer 110 was nitrided by a depth of about 3 nm.

In this manner, the nitrided condition could be controlled into theoptical characteristics that meet the annealing such as the lightirradiation executed subsequently, by measuring the opticalcharacteristics containing the impurity doped layer 110 and a nitridedlight 600 (see FIG. 8), i.e., by using the light source 120 and thephotometer 130, the computer 320, the control circuit 340, and thecontroller 350 provided to the system in FIG. 4.

The term “meeting” of the optical characteristics described here issimilar basically to that described in Example 1. But the absorbency ofthe light used in the annealing step could be enhanced by coating theimpurity doped layer 110 with an oxidized light 610 before theannealing. Further, the oxidization generated by engagement of an oxygenand a water content in the air at a time of annealing could be preventedcorrespondingly. Thus, such an advantage could also be accompanied thattotal optical characteristics of the impurity doped layer 110 and thenitrided light 600 can be stabilized.

Also, as shown in FIG. 8( c), the surface of the impurity doped layer110 could be oxidized by introducing an oxygen or a gas containing anoxygen as the third substance via the third line 300. At this time, theoptical characteristics of the impurity doped layer 110 and the oxidizedlight 610 could also be controlled into the optical characteristics thatmeet the wavelength of the light used in the annealing such as the lightirradiation executed subsequently, by using the light source 120 and thephotometer 130, the computer 320, the control circuit 340, and thecontroller 350 provided to the system in FIG. 4. It was difficult toprevent the oxidation at a time of annealing, but the introduction ofsuch surface oxidized layer could also be applied by taking a measure,e.g., using a vacuum or an inert gas in the annealing atmosphere.

Here, an example in which the impurity doped layer 110 is directlynitrided and oxidized was explained. But the silicon oxide film or otherfilm may be deposited by the so-called CVD technology, for example, bythe method of introducing SiH₄ and the oxygen via the second line 290used to supply the second substance and the third line 300 used tosupply the third substance respectively. If doing so, a thin film thathas no relevance to the physical properties of the impurity doped layercan also be deposited, and various optical characteristics can beobtained. Also, it is of vital importance in the deposition that theoptical characteristics should be controlled by operating the abovecontrolling system.

Example 8

Next, a method of changing sequentially the annealing conditionsfollowing upon the change in the optical characteristics of the impuritydoped area in the annealing step will be explained hereunder.

Here, as shown in FIG. 9, a laser light source 700 is used as the lightsource, a modulation filter 710 capable of changing a wavelength is usedon this optical path, and a modulated light 720 to follow upon thecondition of the impurity doped layer 110 measure by the photometer 130is irradiated onto the impurity doped layer 110 on the surface of thesolid state base body 100.

The impurity doped layer 110 having a different condition from the solidstate base body is formed to contact the solid state base body 100, andthen a thin nitride film, a thin oxide film, or the like is formed toprotect the impurity doped layer or control the optical characteristics.Then, in annealing the resultant structure by irradiating theelectromagnetic wave such as the light, or the like, it is needless tosay that the impurity doped layer most suitable for the annealing can beformed at first to meet the wavelength peculiar to the laser having acenter wavelength by paying an enough attention as described in theabove embodiments. In addition, it is desired that, in order to get thebest result in the annealing step, the annealing conditions should bechanged to follow the condition of the impurity doped layer that ischanged by the light irradiation.

FIG. 10 shows the condition in which the light absorption coefficient ischanged by a light irradiation time. That is, a behavior in which thelight absorbing characteristic indicated with a curve a prior to thelight irradiation is transferred to a curve b after 10 nsec from thelight irradiation and then transferred to a curve c after 100 nsec isshown.

This indicates that a center of the light absorption is shiftedgradually during the annealing time. Since the light of all wavelengthsis contained as the feature of the annealing executed by using the whitelight, this annealing can respond naturally to the change of this lightabsorption, but all lights containing unnecessary wavelengths must beirradiated for that purpose. Therefore, as explained in Example 5,defects are caused such that a temperature of the overall substrate or atemperature near the surface of the solid state base body is increased,or the like.

Hence, first the laser having a center wavelength near 600 nm in thiscase is used. As shown in FIG. 9, the laser light source 700 having acenter wavelength is provided to this annealing furnace, and then thewavelength is changed in time by the modulation filter 710 provided onthe optical path.

In other words, the light incident from the measuring light source 120is measured by the photometer while the impurity doped layer is beingannealed by irradiating the laser light 700. Then, as shown in FIG. 10,a frequency of the irradiated (modulated) light 720 by operating themodulation filter 710 is changed by catching a changing behavior of thelight absorption coefficient. As a result, the light having thewavelength that is always most suitable for the light absorption in theannealing time period could be irradiated onto the impurity doped layer110 that contacts the surface of the solid state base body 100, wherebyan annealing efficiency could be maximized. This indicates that theirradiated energy is seldom absorbed by the portion except the impuritydoped layer. It is possible to say that, in order to form the “shallowjunction” in the semiconductor industry as the major application fieldof the present invention, this method should be an ideal method that hasa highest energy efficiency and can form an extremely shallow junctiondepth when finished.

Example 9

Next, Example 9 of the present invention will be explained hereunder.

In above Example 8, the method of modulating the wavelength of the lightfollowing upon the change of the optical characteristics during theannealing in addition to the optical characteristics of the impuritydoped layer was explained. In this Example, the impurity doped layer asthe doping layer should be formed to meet the wavelength of the laserthat is easily available industrially.

Concretely the method that has already been explained in Example 7belongs to this concept.

In other words, as already explained with reference to FIG. 6, theimpurity doped layer to set a wavelength range in which the lightabsorption coefficient is high can be formed by the formation of theimpurity doped layer. When the plasma doping method is employed as thismethod, as explained in Example 3, the impurity doped layer that canhave the large light absorption coefficient near the wavelength of theused laser by changing several parameters to change the plasmaconditions can be formed.

According to this method, predetermined optical characteristics (herethe light absorption coefficient is considered) can be obtained finallyby observing always the surface of the solid state base body 100 (seeFIG. 4) in the state that the plasma is being generated during theplasma doping (so-called InSitu state), to change the plasma parameters,as shown in Example 4.

Also, the doping is applied to the surface of the solid state base body100 for a predetermined time, e.g., 5 sec, then the plasma irradiationis stopped once, then the optical characteristics are derived bymeasuring the light from the light source 120, then the parameters ofthe plasma explained in Example 3 are changed by feeding back theresult, and then the impurity doped layer 110 is formed by executing theplasma doping for next 5 second, for example. The opticalcharacteristics of the impurity doped layer that meets the wavelength ofthe selected laser light can be set by repeating these steps.

Also, in the above embodiments, the impurity doping step and theannealing step are executed by the separate furnace. But these steps maybe executed by the same furnace.

Also, an adjustment of the optical characteristics of the impurity dopedlayer in the annealing step can be accomplished by a thin film formationby the normal-pressure plasma. In other words, when the opticalcharacteristics of the impurity doped layer are measured and then thethin film formation on the surface following upon the change of thephysical properties of the impurity doped layer is executed tocompensate the change of the optical characteristics of the impuritydoped layer itself caused due to the progress of the annealing, thelight absorbency into the impurity doped layer can be increased to meetthe annealing conditions.

The present invention is explained in detail with reference to theparticular embodiments, but it is apparent for the person skilled in theart that various variations and modifications can be applied withoutdeparting from a spirit and a scope of the present invention.

The present application is based upon Japanese Patent Application No.2003-331330, filed on Sep. 24, 2003 and Japanese Patent Application No.2004-065317, filed on Mar. 9, 2004, the contents of which areincorporated herein by reference.

INDUSTRIAL APPLICABILITY

The impurity doping method and system of the present invention is ableto realize formation of a fine semiconductor area such as formation of ashallow junction, formation of a super thin film, or the likeeffectively not to rise a substrate temperature, and is effective forformation of the electronic device such as capacitor, varistor, diode,transistor, coil, or the like or effective for the case where theimpurity is doped selectively into a large-size substrate such as aliquid crystal substrate, or the like without a temperature rise.

1-31. (canceled)
 32. An impurity doping method, comprising the steps of:doping an impurity into a surface of a solid state base body; measuringan optical characteristic of an area into which the impurity is doped;selecting annealing conditions based on a measurement result to meet theoptical characteristic of the area into which the impurity is doped; andannealing the area into which the impurity is doped, based on theselected annealing conditions.
 33. The impurity doping method accordingto claim 32, wherein the step of doping the impurity contains a plasmadoping step.
 34. The impurity doping method according to claim 32,wherein the step of doping the impurity contains an ion implanting step.35. The impurity doping method according to claim 32, wherein themeasuring step is executed prior to the annealing step.
 36. The impuritydoping method according to claim 32, wherein the measuring step isexecuted in parallel with the annealing step.
 37. The impurity dopingmethod according to claim 32, wherein the annealing step is divided intoplural numbers of time, and the measuring step is executed among theannealing step.
 38. The impurity doping method according to claim 32,wherein the step of selecting the annealing conditions contains a stepof causing the annealing conditions to change sequentially followingupon a change of the optical characteristic of the impurity doped areaduring the annealing step.
 39. The impurity doping method according toclaim 32, wherein the impurity doping step is divided into pluralnumbers of time, and the measuring step is executed among the impuritydoping step.
 40. An impurity doping method, comprising the steps of:doping an impurity into a surface of a solid state base body; measuringan optical characteristic of an area into which the impurity is doped;adjusting the optical characteristic based on a measurement result tomeet annealing conditions; and annealing an area into which the impurityis doped.
 41. The impurity doping method according to claim 32, whereinplasma doping conditions are controlled such that optical constants meeta light irradiation executed after the plasma doping step, whilemonitoring the optical constants of the area into which the impurity isdoped.
 42. The impurity doping method according to claim 40, whereinplasma doping conditions are controlled such that optical constants meeta light irradiation executed after the plasma doping step, whilemonitoring the optical constants of the area into which the impurity isdoped.
 43. The impurity doping method according to claim 32, wherein theion implanting step is controlled such that optical constants meet alight irradiation executed after an ion implantation, while monitoringthe optical constants of the area into which the impurity is doped. 44.The impurity doping method according to claim 40, wherein the ionimplanting step is controlled such that optical constants meet a lightirradiation executed after an ion implantation, while monitoring theoptical constants of the area into which the impurity is doped.
 45. Theimpurity doping method according to claim 32, wherein the ion implantingstep is controlled such that optical constants meet a light irradiationexecuted after an ion implantation, while monitoring the opticalconstants of the area into which the impurity is doped.
 46. The impuritydoping method according to claim 40, wherein the ion implanting step iscontrolled such that optical constants meet a light irradiation executedafter an ion implantation, while monitoring the optical constants of thearea into which the impurity is doped.
 47. The impurity doping methodaccording to claim 32, wherein the measuring step is a step of using anellipsometry.
 48. The impurity doping method according to claim 40,wherein the measuring step is a step of using an ellipsometry.
 49. Theimpurity doping method according to claim 47, wherein the step of usingthe ellipsometry contains an ellipsometry analyzing step of calculatingboth a thickness of the impurity doped layer and optical constants (arefractive index n and an extinction coefficient k).
 50. The impuritydoping method according to claim 48, wherein the step of using theellipsometry contains an ellipsometry analyzing step of calculating botha thickness of the impurity doped layer and optical constants (arefractive index n and an extinction coefficient k).
 51. The impuritydoping method according to claim 49, wherein the ellipsometry analyzingstep contains an analyzing step employing a refractive index wavelengthdispersive model using any one of K-K (Kramers-Kronig) analysis,Tauc-Lorentz analysis, Cody-Lorentz analysis, Forouhi-Bloomer analysis,MDF analysis, band analysis, Tetrahedral analysis, Drude analysis, andLorentz analysis.
 52. The impurity doping method according to claim 50,wherein the ellipsometry analyzing step contains an analyzing stepemploying a refractive index wavelength dispersive model using any oneof K-K (Kramers-Kronig) analysis, Tauc-Lorentz analysis, Cody-Lorentzanalysis, Forouhi-Bloomer analysis, MDF analysis, band analysis,Tetrahedral analysis, Drude analysis, and Lorentz analysis.
 53. Theimpurity doping method according to claim 32, wherein the annealing stepis a step of irradiating an electromagnetic wave.
 54. The impuritydoping method according to claim 40, wherein the annealing step is astep of irradiating an electromagnetic wave.
 55. The impurity dopingmethod according to claim 32, wherein the annealing step is a step ofirradiating an electromagnetic wave.
 56. The impurity doping methodaccording to claim 40, wherein the annealing step is a step ofirradiating an electromagnetic wave.
 57. The impurity doping methodaccording to claim 55, wherein the annealing step is a step ofirradiating a light.
 58. The impurity doping method according to claim56, wherein the annealing step is a step of irradiating a light.
 59. Theimpurity doping method according to claim 57, wherein the step of dopingthe impurity is a step of doping an impurity such that a lightabsorption coefficient of the area into which the impurity is dopedexceeds 5 E⁴ cm⁻¹.
 60. The impurity doping method according to claim 58,wherein the step of doping the impurity is a step of doping an impuritysuch that a light absorption coefficient of the area into which theimpurity is doped exceeds 5 E⁴ cm⁻¹.
 61. The impurity doping methodaccording to claim 33, wherein the plasma doping step contains a step ofcontrolling at least one of a power supply voltage applied to theplasma, a composition of the plasma, and the ratio between anirradiation time of the plasma containing a dopant substance and anirradiation time of the plasma not containing the dopant substance. 62.The impurity doping method according to claim 41, wherein the plasmadoping step contains a step of controlling at least one of a powersupply voltage applied to the plasma, a composition of the plasma, and aratio between an irradiation time of the plasma containing a dopantsubstance and an irradiation time of the plasma not containing thedopant substance.
 63. The impurity doping method according to claim 60,wherein the plasma doping step contains a step of controlling acomposition of the plasma by changing a mixture ratio between animpurity substance to constitute the plasma and an inert substance or areactive substance as a substance mixed with the impurity substance, tocontrol the optical characteristic of the area into which the impurityis doped.
 64. The impurity doping method according to claim 62, whereinthe plasma doping, step contains a step of controlling a composition ofthe plasma by changing a mixture ratio between an impurity substance toconstitute the plasma and an inert substance or a reactive substance asa substance mixed with the impurity substance, to control the opticalcharacteristic of the area into which the impurity is doped.
 65. Theimpurity doping method according to claim 33, wherein the plasma dopingstep sets the optical constant of the area into which the impurity isdoped such that electrical activation of the impurity contained in thearea into which the impurity is doped is accelerated and an energyabsorption into the solid state base body is suppressed.
 66. Theimpurity doping method according to claim 41, wherein the plasma dopingstep sets the optical constant of the area into which the impurity isdoped such that electrical activation of the impurity contained in thearea into which the impurity is doped is accelerated and an energyabsorption into the solid state base body is suppressed.
 67. Theimpurity doping method according to claim 33, wherein the plasma dopingstep sets the optical constant of the area into which the impurity isdoped such that electrical activation of the impurity contained in thearea into which the impurity is doped is accelerated and an energyabsorption into the solid state base body is suppressed.
 68. Theimpurity doping method according to claim 41, wherein the plasma dopingstep sets the optical constant of the area into which the impurity isdoped such that electrical activation of the impurity contained in thearea into which the impurity is doped is accelerated and an energyabsorption into the solid state base body is suppressed.
 69. Theimpurity doping method according to claim 33, wherein the plasma dopingstep sets the optical constant of the area into which the impurity isdoped such that electrical activation of the impurity contained in thearea into which the impurity is doped is accelerated and an energyabsorption into the solid state base body is suppressed.
 70. Theimpurity doping method according to claim 41, wherein the plasma dopingstep sets the optical constant of the area into which the impurity isdoped such that electrical activation of the impurity contained in thearea into which the impurity is doped is accelerated and an energyabsorption into the solid state base body is suppressed.
 71. An impuritydoping system, comprising: an impurity doping means for doping animpurity into a surface of a solid state base body; a measuring meansfor measuring an optical characteristic of an area into which theimpurity is doped; and an annealing means for annealing the area intowhich the impurity is doped.
 72. The impurity doping system according toclaim 71, wherein the impurity doping means is a plasma doping means fordoping the impurity into the surface of the solid state base body. 73.The impurity doping system according to claim 71, wherein the impuritydoping means is an ion implanting means for implanting the impurity intothe surface of the solid state base body.
 74. The impurity doping systemaccording to claim 72, further comprising: a doping controlling meansfor controlling the plasma doping means based on measurement results ofthe measuring means.
 75. The impurity doping system according to claim73, further comprising: a doping controlling means for controlling theion implanting means based on measurement results of the measuringmeans.
 76. The impurity doping system according to claim 71, furthercomprising: an annealing controlling means for controlling the annealingmeans based on measurement results of the measuring means.
 77. Theimpurity doping system according to claim 71, further comprising: afeedback mechanism for feeding back a measurement result of themeasuring means to any one of the annealing controlling means or theimpurity doping controlling means.
 78. The impurity doping systemaccording to claim 77, wherein the feedback mechanism executes afeedback of a measurement result in-situ.
 79. The impurity doping systemaccording to claim 78, wherein the feedback mechanism executes asampling inspection at a high speed, and executes an additional processsuch as an additional doping, annealing conditions relaxation, or thelike if a result is not good.
 80. The electronic device formed by dopingan impurity by using the impurity doping system set forth in claim 32.81. The electronic device formed by doping an impurity by using theimpurity doping system set forth in claim
 40. 82. The electronic deviceformed by doping an impurity by using the impurity doping system setforth in claim 71.